Tuning mechanism



L. D. SACRE TUNING MECHANISM May 6, 1952 7 Sheets-Sheet 1 Filed Aug. 20, 1945 INVENTOR.

M y 9 L. D. SACRE 2,595,984

TUNING MECHANISM Filed Aug. 20, 1945 7 Sheets-Sheet 2 I l l I I INVENTOR. 39 [90 i Jacre 6194 l 6196 L. D. SACRE TUNING MECHANISM May 6, 1952 7 Sheets-Sheet 4 Filed Aug. 20, 1945 M y 5, 1952 D. SACRE 2,595,984

TUNING MECHANISM Filed Aug. 20, 1945 7 Sheets-Sheet 5 INVENTOR. c522 are Uffya y 6, 1952 Q L. D. SACRE 2,595,984

' TUNING MECHANISM Filed Aug. 20, 1945 7 Sheets-Sheet 6 3%, 12.95 f yc 121 a ap lo. I- 19/ 1.9/6

116a INVENTOR. //5e Zea fl czcre y 6, 1952 1.. D. SACRE 2,595,984

TUNING MECHANISM Filed Aug. 20, 1945 7 Sheets-Sheet 7 1 N VEN TOR.

Patented May 6, 1952 TUNING MECHANISM Leo D. Sacre, Park Ridge, 111., assignor to Motorola, Inc., a corporation of Illinois Application August 20, 1945, Serial No. 611,588

7 Claims. 1

The present invention relates to control apparatus and more particularly to an improved mechanism for moving the tuning shaft of tunable wave signallingapparatus to any one of a number of predetermined settings within a predetermined rotational range. Specifically, this invention relates to improvements in apparatus of the character disclosed in Elliott Patent No. 2,249,753, granted July 22, 1941.

It is an object of the present invention to provide an improved mechanism for automatically tuning tunable wave signaling apparatus, such, for example, as a radio receiver, which is compact in arrangement, is of simple and inexpensive construction and is positive and reliable in operation.

t is another object of the invention to provide an improved mechanism of the character described which is automatically operable to move a tuning shaft with exact precision to any selected one of a number of predetermined settings within the rotational range of the shaft.

According to a further and more specific object of the invention, there are provided, in an electrified push button tuning mechanismof the type utilizing shaft stopping only during rotation of the shaft in one direction, improved facilities for determining the stop points, i. e. the points corresponding to the predetermined shaft settings, with precision accuracy.

It is a still further object of the invention to provide in a mechanism of the character described, an improved and exceedingly simple control unit for determining one of settings of the tuning shaft with precision accuracy.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

Fig. 1 schematically illustrates an improved tuning mechanism characterized by the features of the present invention;

Fig. 2 is a front view of one structural embodiment of the present improved mechanism;

Fig. 3 is a fragmentary detail view illustrating certain parts of the mechanism shown in Fig. 2;

Fig. 4 is a fragmentary sectional view taken along the lines 4-4 in Fig. 2;

Fig. 5 is a top sectional view taken along the lines 5-5 in Fig. 4;

Fig. 6 is a fragmentary sectional view taken along the lines 66 in Fig. 2; 1

Fig. 7 is a fragmentary view partially in section taken along the lines 1--'| in Fig. 4;

Fig. 8 is a fragmentary detail view in section illustrating the parts making up a part of one of the control units embodied in the mechanism;

Fig. 9 is an exploded view of the control unit parts shown in Fig. 8;

Fig. 10 is an explosion view of the parts making up another part of the control unit partially shown in Fig. 8;

Fig. 11 is a top view of a modified structural embodiment of the present improved mechanism;

Fig. 12 is a front view partially in section illustrating further details of the mechanism shown in Fig. 9;

Fig. 13 is a side view of the mechanism shown in Fig.9;

Fig. 14 is a fragmentary detail view in section taken along the lines IL -l2 in Fig. 10; and

Fig. 15 is a perspective view better illustrating certain of the parts of the modified mechanism.

Referring now to the drawings, and more particularly to Fig. 1 thereof, the present improved mechanism is there illustrated in its use to impart any one of a number of predetermined angular settings to the settable shaft ll of adjustable tuning means H] which may be electrically included in tunable wave signaling apparatus such, for example, as a conventional radio broadcast receiver. The tuning means may comprise theusual gang-connected condensers, through adjustment of which the receiver is selectively tuned to receive different signals within a predetermined frequency band. These condensers may be of the conventional degrees type, such that the tuning shaft II has a 180 degree rotational range between the limits thereof. This tuning shaft is connected through the usual gear train l2 to the output shaft 2| of the present improved tuning mechanism, which gear train serves to convert high speed rotation of the shaft I3 into low speed rotation of the tuning shaft II, with a predetermined speed ratio therebetween. Manual adjustment of the tuning means [0 to settings other than those automatically obtainable through operation of the tuning mechanism, may be effected through operation of a tuning knob 12a carried by the shaft 2 I.

In brief, the present improved tuning mechanism comprises a reversible driving motor 36 arranged to drive the tuning shaft II in either For the purpose of stopping the tuning shaft 7 II after it has been rotated to any one of a number of predetermined settings within its rotational range, a plurality of control units I4 are provided, which individually correspond to these settings and are arranged for selective activation under the control of the push buttons 25. One of these units, i. e. the unit I ia is schematically illustrated in Fig. 1 of the drawings as comprising a pair of rotatable camming elements I5a and lea having the function of determining one predetermined setting of the shaft II with approximate and precision accuracy, respectively. These elements haverotational ranges respectively correspondingto the predetermined rotational range of the shaft II. More specifically, the camming element I6a is carried by the shaft 2|. for high speed rotation therewith and has a rotational range several times greater than that of the low speed camming element I5a. The latter camming element is mounted for rotation with a shaft I3 which is driven from the shaft 2| through speed reducing gears iii, 52, M and 45. Assuming that the drive ratio between the shafts-2| and the same as that between the shafts 2| and II, then the two shafts I3 and II have the same rotational ranges. The control unit I4a further comprises a latching element lla pivotally supported by the stationary shaft 35 and having cam following and locking noses 2la and 34a respectively cooperable with the peripheries of the two camming elements. The nose 34a is also cooperable with the locking shoulder 330. provided along the periphery of the camming element ita' to arrest rotation of the shafts I3 and 2| when these shafts and the connected tuning shaft l are rotated to the predetermined position represented by the control unit Ma. Normally the noses 2la and 34a of the latching element lla are held out of engagement with the peripheries of the two camming elements through the action of a biasing finger 29c which forms a part of a comb-like biasing spring 23 described more fully below, and projects into a recess 28a formed at the lower end of the latching element. The latching element Ila. is arranged to be rotated to engage its two noses with the peripheries of the camming elements through energization of an electromagnet I9a. This magnet is arranged to be energized under the control of the push button a and coacts with an armature part IBa projecting laterally from the latching element Ila in producing rotation of the latching element. The other four magnets fish, I90, Nd and its respectively associated with the four other control units Mb, I40, IM and Me, and arranged for selective energization under the control of the push buttons 29b, 26c, 28d, and 20e, are also illustrated in Fig. 1 of the drawing to indicate the selective shaft positioning function of the mechanism.

As'indicated above, the latching nose 34a is I3 is.

arranged to coact with the latching shoulder 33a to arrest rotation of the shafts I3 and 2|. This, of course, means that the two shafts 2| and I3 must be rotated in a counterclockwise direction in order to effect locking engagement of this nose with the shoulder 33a. Further, since the predetermined shaft position represented by the control unit I la may be approached by rotation of the shafts I3 and 2| in either direction, it is necessary to provide facilities for reversely rotating the various rotatable parts of the mechanism in response to rotation of the shaft I3 in one direction past the predetermined setting to which the control unit Ma corresponds. To this end the camming element I511. is provided with peripheral camming surfaces 22a and 23a of two different diameters. Further to this end, means comprising a rocker bar 50 arranged to be controlled in accordance with the angular setting of any one of the latching elements Il, are provided for selectively energizing the relay 46 to in turn control, on a selective basis, the energization of the two motor field windings 36a and 36b. Specifically, the rocker bar 50 is pivotally supported by the stationary shaft 35, carries a movable contact 52 cooperable with a stationary contact 53, and is biased by means of a coil spring 5| normally to hold the contact 52 out of engagement with the contact 53. Energizing current for the motor 36, the relay 45 and the magnets I9 may be obtained' from any suitable current source such, for example, as the battery 54.

Briefly to consider the mode of operation of the present improved mechanism, it may be assumed that it is desired to adjust the tuning means Ill to the particular setting represented by the control unit I la. at a time when the nose 2la is disposed opposite the peripheral surface 22a of the camming element [5a. To effect adjustment of the tuning means III to the desired setting, it is only necessary to actuate the push button 20a, thereby to complete an obvious circuit for energizing the magnet I911 and a parallel circuit for energizing the motor windings 36b and 360 through the contacts Al and 48 of the de-energizedrel-ay 66. When thus energized, the motor 36 functions to drive the two shafts 2| and I3 in a clockwise direction, and to drive the tuning shaft II toward the desired setting through the driving connection afforded by the slip clutch 55, the gears 38, 39 and 40, and the described gear train I2 interconnecting the shaft 2| with the tuning shaft I In response to-energization of the magnet I941, the latching element Ila is pivoted in a clockwise direction against the biasing action of the spring finger 29a and the coil spring 5| to bring the nose 21a thereof into engagement with the cam surface 22a. Coincident with such rotation of the latching element Ila, the armature part I8a pivots the rocker bar 50 to move the contact 52 toward the stationary contact 53. So long as the nose 27a of the latching element Ila engages the cam surface 22a, however, the rocker bar 50 is not rotated to produce engagement of the con tacts 52 and 53.

During the described operation of the mechanism, the camming element l6a is rotated at a speed several times greater than the speed of rotation of the camming element I511, the particular speed ratio being determined by the stepdown ratio through the gears 4|, 42, M and 45 interconnecting the shaft 2| with the shaft I3. For example, a speed ratio of 14:1 may be provided .betweenthe canirning element Mia and the camming elementlSa. This, of course, means that the camming element Hid may be required to rotate through several revolutions while the calm ming surface 22a is being moved beneath the nose 27a. In this regard it is noted that the latching nose Bria is held out of engagement with the cam periphery Sta so long as the opposed nose 27a. is riding upon either of the two cam peripheries 22a or 2%.

When thecams lid and ifia are rotated to the position illustrated in Fig. 1 of the drawings, the latching element lid is freed for further rotation in a clockwise direction under the influence of the energized magnet Isa. During such rotation of the latching element lie, the camming elements Ilia and Mia are further rotated in a clockwise direction so that the nose Zia engages the leading end of the cam surface 23a to stop the latching element rotation. As this latching element is further rotated in the manner described, the contact 52 is engaged with the contact 53 to complete an obvious circuit for energizing the relay 56. In operating, this relay opens its contacts 47, 43 to de-energize the motor windings 36b and SEC, and closes its contacts 4?, 59 to complete a circuit for energizing the field winding 36a in series with the armature winding 360. Thus, the direction of rotation of the motor 36 is reversed to produce counterclockwise rotation of the shafts 22, i5; and H. After a small increment of such counterclockwise rotation, the nose 21a rides down the incline 25a, permitting further counterclockwise rotation of the latching element [Ta to a position wherein the nose 34a is in the path of movement of the shoulder 33a. The nose 21a thereafter engages the cam shoulder 26a and drops into the notch in this cam, permitting full engagement of the opposite nose 3411 with the surface 3 i a of the carnming element lfia. Finally, the camming element ifia is rotated to bring the shoulder did against the nose 34o: permitting the two noses 34a and Zia to be pulled to the bottom of the notches in the camming elements Hid and 25d under the influence of the energized magnet a. When this occurs, the entire mechanism back to the gear 38 of the gear train is locked against further rotation. Operation of the motor 35 continues so long as the push button 253a is depressed, rotation of the motor armature being permitted by slippage between the engaged friction elements of the clutch 55. When the push button 28a is released, the magnet [9d, the relay 4B and the windings36a and 360 of the motor 36 are deenergized. Upondeenergization of the magnet lfia, the rocker bar 5!] and the latching element Ha are retracted to their respective normal positions under the influence of the spring 5! and the biasing finger 29a.

Assume now that at the time the push button a is depressed to initiate adjustment of the tuning means it to the particular setting corresponding to the control unit Ma, the shaft [3 occupies a setting wherein a segment of the camming surface 23a is opposite the nose 21a of the latching element Ha. In this case, the magnet ISa, when energized, rotates the latching element Ha to bring the nose Zia into engagement with the cam surface 23a and thus rock the bar 50 to a position wherein the contacts 52 and 53 are engaged. Accordingly, the relay 45 is immediately energized in response to operation of the button 23a. toproduce counterclockwise roa i h camp n el ents 15:; and M a. As

such rotation of t .Q mm e e ments o ee the nose 21a rides down th incline 25ato permit ockin n a emen of the am s w d r 31 wi h the nos 3% n th exact m n e explained above. Thus, in the second case just considered, operation of thetuning means to the setting represented ;by the control unit I ia is effected withoutreversing the direction of rotation of the drivinam r From the above explanation it will be understood that regardless of the direction from which the predetermined setting of the shaft Ii is approached, the two camming elements I Ea and I64 jointly cooperate with the latching element Ila to arrest rotation of the shaftwhen the predetermined settingis imparted thereto. Specifically, the low speed camming element [5 has the function of selecting the predetermined shaft setting with approximate accuracy in that it determines the particular revolution of the shaft 2 during which the camming element lfia maybe lockingly engaged with the latching element Ila. The last mentioned camming element, on the other hand, determines the predetermined shaft setting with precision accuracy by virtue of the high speed ratio between this element and the shaft i l. Thus, if a speed ratio of 14;1 is provided between the shafts 2i and II, and a one degree (1) error is inadvertently obtained in producing locking engagement between the nose 34a and the cam shoulder 33a, an error of only one-fourteenth of a degree occurs in the positioning of the shaft H. Thus, egrtrerne accuracy may be obtained in stopping the tuning shaft in a desired setting. even though rather wide tolerances are provided in thedesign of the two camming elements and the latching element. For example, considerable slop may be provided between the nose Zia and the shoul der 26a with which this nose is engageable. In fact, and as pointed out below, the camming element I 5:; is not rigidly locked against rotation relative to the shaft l3, but is only frictionally restrained against free rotation about this shaft. Again, slight discrepancies in the position of the shoulder 33a. along the 'camming element [6a relative to the latching element nose 35a result in only non-appreciable errors in setting the shaft H to the particular position to which the control unit Ma corresponds.

In the mechanical embodiment of the present improved mechanism illustrated in FigsfZ to 10, inclusive, of the drawings, the various components of the several control units 14 are supported by and between two frame members and 57 which are held in spaced apart relationship by means of cross members Eliia and 59b and a spacing post til. As best shown in Fig. 2 of the drawings, the frame member 51 is mounted upon the right end of a motor housing 58 within which the parts or" the motor 36 are disposed. The front wall 53a of the motor housing 58 is also employed to support the relay 46 and the contact spring assembly associated with the armature of this relay. The stationary shaft 35 upon which the latching elements H are pivotally supported and the two rotatable shafts l3 and 2! extend between the frame members 55 and 5?, the two latter shafts having their ends suitably journalled in openings through the frame members. The gears 38, 39 and Gil connecting the motor shaft 31 in driving relationship with the high speed cam shaft iii are disposed to the side of the frame member 5?. More specifically, the gear 3% is rotatably mounted upon the motor shaft 31 and is clutched to-this shaft through the slip clutch 55 which comprises a dished spring 5512 reacting between the gear 38 and a collar 55a to press the gear 38 against a friction disc 38a. which abuts a shoulder provided along the shaft 31. The gears 4|, 42, 44 and 45 interconnecting the shaft 2| with the low speed shaft I3 are mounted just inside the frame member 56, with the two gears 42 and 44 being journalled for rotation about the stationary shaft 35.

As best shown in Figs. 2 and of the drawings, the mechanism comprises five control units I4a, I41), I40, Md and Me, and a sixth control unit I4 the details of which are illustrated in Fi 6 of the drawings, having the function of determining the rotational ranges of the shafts I3 and 2|. The camming elements I5 and I6 of the respective control units are respectively carried by the radially spaced shafts I3 and 2|. More in detail, the camming elements I6 are arranged in stacked relationship along a sleeve 62 having an enlarged head 63a which is pinned to the shaft 2I by means of a pin 69. These camming elements, together with the camming element I61, are clamped against rotation relative to the shaft 2| by means of a releasable clamping assembly which comprises a plate 63 threaded on to the left end of the sleeve 62, a floating clamping plate II and a clamping lever ID. This lever is of U-shaped cross-sectional configuration and the base wall 10a thereof is apertured'to receive the shaft 2| and thus permit rocking engagement of the lever with a pin I3 extending transversely through the shaft 2|. In order to prevent relative rotation between the lever III and the shaft 2|, this shaft is flatted along opposite sides thereof as indicated at 2Ia and the edges of the aperture through the base wall 10a. of the lever are correspondingly fiatted to coact with the flats 2Ia in providing locking engagement between the two parts I0 and 2 I. A screw I2 threaded through the lever base wall 100. and engageable with the clamping plate II is utilized to rock the lever "I0 about the pin 13 and thus exert clamping pressure upon the stacked camming elements I6. Access to this screw for screw driver adjustment thereof 'is permitted through the provision of an aperture 51a in the frame member 51.

The camming elements I6 are held in spaced apart relationship axially of the shaft 2| by means of spacing discs 68 interposed therebetween. Each camming element is of ring-like configuration and is held in a position radially spaced from the sleeve 32 by an assembly of the character illustrated in Figs. 8, 9 and 10 of the drawings. These assemblies include identical parts. In brief, that supporting the camming element Ifia comprises an inner ring 54a supporting a floating ring 65a of lesser thickness which is interlocked with the camrning element I6a. To obtain the desired interlock between the two last-named parts, the ring 65a is provided with an ear 66a, Fig. 4, which projects into a correspondingly shaped recess provided at the inner edge of the camming element Ita. Thus, the two parts I611. and 5501. are locked against relative rotation, but are rotatable as a unit about the parts 64a and 62. A dished spring Washer 61a is interposed between the floating ring 65a and the adjacent spacing disc 68 to restrain the elements Ito and 65a against rotation relative to the sleeve 62 when the lever 'II) is actuated to relieve the clamping pressure upon the stacked 8 camming elements. This washer is deformed during assembly of the elements upon the sleeve 62 to react between the spacing disc 68 and the ring 65a and thus thrust this ring against the adjacent spacing disc 68.

In the assembly of the mechanism, the described parts 64, 65, 6! and I6 of each control unit are stacked upon the sleeve 52 with the spacing discs 68 interposed therebetween, following which the clamping plate 63 is threaded onto the end of the sleeve 52 to clamp the rings 54 and the inner peripheries of the discs 68 against the sleeve head 62a and thus restrain the parts 62, 64 and 68 against relative rotation. After the mechanism is completely assembled, the camming elements I6 are adjusted to predetermined angular settings relative to the shaft 2| in the manner explained below. These settings are retained by tightening the screw I2 against the clamping plate II to pivot the lever II! about the pin I3 and thus exert clamping pressure upon the plate II at two opposed points therearound, such that the camming elements I6 are locked in their adjusted positions against rotation relative to the shaft 2 I.

As will be evident from a consideration of Figs.

5 and 10 of the drawings, the assemblies for supporting the camming elements I5 upon the sleeve M are identical with those for supporting the camming elements I6 upon the sleeve 62. Thus, the parts I5, 71, 78, I9 and 16 carried by the sleeve I4 correspond respectively to the parts I6, 64, 65, 67 and 58 carried by the sleeve 62. A second sleeve I5 interposed between the gear 45 and the left spacing disc I6 is utilized to clamp the stacked discs I6 and inner rings TI against the head 14a of the sleeve I4 to prevent relative rotation therebetween. In this regard it is noted that aside from the frictional restraining forces provided by the dished spring washers 19, no facilities are provided for restraining the camming elements I5 against rotation relative to the shaft I3. Thus, these elements may be adjusted to desired angular settings relative to the shaft I3, and are retained in these settings solely by the spring washers I9.

As previously indicated, the latching elements are rotatably supported by the stationary shaft 35. Specifically, these elements are spaced along this shaft with spacing washers interposed therebetween and are held in predetermined positions axially of the shaft by means of collars BI and 82 set screw mounted upon the shaft. The armature parts I8 of the latching elements project laterally therefrom to positions opposite the pole face ends of the magnets I9. These magnets are mounted in spaced apart positions along the two cross members 59a and 59b of the frame structure. More specifically, and as best shown in Figs. 4 and '7 of the drawings, the two magnets I91) and I are mounted upon the cross member 59a, and the armature parts I81) and I8d of the latching elements Ill) and Na respectively extend upward and then laterally in opposite directions for cooperation with the pole face ends of these magnets. The three magnets I9a, I90, and I96 are similarly mounted upon the cross member 591) beneath the shaft 2|. With this arrangement, the armature part I80 of the middle latching element He may project straight down for cooperation with the pole face end of the magnet ciated magnets |9a and We. As. shown in dash lines in Fig. 4 of the drawings, the five identified latching elements are normally'biased to positions out of engagement with their respectively associated camming elements by means of the fingers 29a, 29b, 29c, 29d and 2920f a resilient comb-like biasing element 29 which is rivet connected to a bracket 59c mounted upon the cross member 5941. The ends of these fingers enter recesses 28 in. the noses 2'! of the latching elements and. eachnormally occupies the unstressed setting of the finger 2922 as shown in Fig. 4 of the drawings. When in this position, the nose ends of each latching element are within the confines of the outer peripheral edges of the spacing discs 58 and 16-. these discs serve to maintain the noses of the latching elements in alignment with their respective associated camming elements. As best shown in Fig. 2 of the drawings, the stationary contact 53 which coacts with the movablecontact 52 to control the energization of the reversing relay 46 is carried at the free end of a resilient contact arm 53a mounted upon the frame member 55 and insulated therefrom in any suitable manner.

Referring now more particularly to the control unit M which is provided to determine the rotational ranges of the shafts l3 and 2|, this unit is illustrated in Fig. 6 of the drawings as comprising a camming element I5) carried by the shaft l3 and a camming element I61 carried directly by the head 62a of the sleeve 62. These two elements are both locked against rotation relative to the shafts l3 and 2| upon which they are respectively mounted. Bridging the two camming elements and cooperable therewith to lock the mechanism against rotation at the respective limits of the rotational ranges of the two shafts, is a latching element ll which is pivotally supported by the stationary shaft 35. This element has a cam follower nose 25f engaging the periphery of the camming element I5 and a locking' nose 34f engageable with the shoulders 32 f and 33] provided at the junctions between the small and large diameter peripheries 3| and 30 of the camming element Hi to determine the limits of the rotational ranges of the two shafts l3 and 2|. The latching element I1 is biased toward engagament with the peripheries of the associated camming elements by means of a resilient biasing strip 29 fixedly mounted upon the bracket 59c and having a free end engaging the latching element adjacent the nose end 25 thereof.

The manner in which the various control units Ma, Mb, Mc, Md and Me individually function to determine different predetermined settings of the shaft H is exactly the same as explained above with reference to Fig. 1 of the drawings. In this regard it will be understood that the control units are selectively activated to determine the positions imparted to the shaft I during operation of the mechanism through selective operation of the push buttons 20 to selectively energize the magnets l9. It will also be understood that the control units are mutually non-interfering. Thus, the latching elements ll are restrained out of engagement with their associated camming elements by their biasing fingers 29 so long as their respective associated magnets IS are deenergized. Accordingly, when any one of the magnets is energized, only the associated latching element is rotated to a setting which will ultimately result in stopping of the shaft in the particular angular position corresponding to the operated magnet.

ThllS,

As previously indicated, the camming elements I5 and I6 of each control unit are adjustable relative to the shafts l3 and 2|, respectively, to change the predetermined tuning shaft setting to which the control unit corresponds. Thus, in order to change the shaft setting represented by the control unit Ma, the clamping screw 72 is first unscrewed sufiiciently to permit relative rotation between the camming elements l6 and the shaft 2|. Following this operation, the push button 20a is depressed to effect operation of the mechanism to a setting wherein the latching element noses 34a and 21a are fully engaged with the shoulders 33c and 26a, all in the exact manner explained above. Following this operation, and with the magnet |9a still energized, the shaft H is manually operated to the particular setting which it is desired to thereafter obtain automatically through operation of the control unit Ma. During such rotation of the shaft II and the elements connected in driving relationship therewith, the camming elements lfia and [5a are held against rotation by the latching elements Ila. Specifically, the ring 64a which is locked to the shaft 2|, is rotated within the ring 65a which is interlocked with the camming element l6a. Similarly, the inner ring Tia which is locked to the shaft l3 for rotation therewith, is rotated within the spacing ring 18a which is in-- terlocked with the camming element l5a. Since all of the spacing discs 68 and 16 are likewise rotated with the shafts 2| and I3, the camming elements, other than the elements |5a and I'Sa, are rotated with their respective shafts due to the frictional locking provided by the spring washers 61 and 19. Thus, only the positions of the camming. elements |6a and i521, relative to the shafts 2| and I3 are changed in response to manual operation of the mechanism. After the mechanism has been operated to impart the de sired setting to the tuning means [0, as determined by the particular station which it may be desired to receive, the push button 20amay be released to effect deenergization of the magnet |9a and resulting release of the latching element Ila. The camming elements of the other four control units may be similarly adjusted as desired for the purpose of changing the predetermined tuning shaft settings respectively represented thereby. After all such adjustments are completed, the screw 12 may be threaded into the lever H! for the purpose of relocking the camming elements 6 against rotation relative to the shaft 2|.

Referring now more particularly to the manner in which the control unit it) functions to determine the rotational ranges of the shafts |3 and 2|, it is pointed out that these rotational ranges are determined by the angular spacing between the recesses 24f and 26 with which the camming nose 25f of the latching element IIf is engageable. Thus, so long as this nose is engaging the cam 15 at a po nt along the peripheral segment 23 thereof, the locking nose MI is held in a position away from the large diameter periphery 351 of the locking cam l 5 Accordingly, both of the shafts l3 and 2| are free to rotate. Assume now that the shafts l3 and 2| are rotating in a counterclockwise direction and that such rotation is continued until the nose 25f enters the recess 26 in the camming element l5 As this nose approaches the bottom of the recess 26), the locking nose 34) is moved into the path of movement of the shoulder 33f to engage the same and stop operation of the mechanism and thus lockingnose 341 of the latching element IIf shall be moved into the path of rotation of one of the two shoulders 32/ and 33]. The camming element I6;f, on the other hand, actually performs the function of locking the mechanism against further operation. Since the latter camming element 'is rotated through a rotational range several times greater than the range of rotation of the cammingelement I), it will be understood thatthe described control unit functions to determine the limits of the shaft rotation ranges with a high degree of accuracy. Also, since the elements I4) and I61 are adjustable on the twoshafts the limits of the rotational ranges may be shifted as desired and in the manner described above with reference to adjustment of the camming elements I5 and I6.

Referring now more particularly to Figs. 11 to 15, inclusive, of 'the drawings, the modified structural embodiment of the present improved mechanism there shown is functionally identical with that illustratedin Figs. 2 to 8, inclusive, and described above. Accordingly, corresponding parts of the two structures have been identified by reference numerals having the same units and tens digits, but'differentiated by the addition of the hundreds digit one to the reference numbers identifying the parts of the modified mechanism. Thus; the frame members I56 and I51 correspond respectively to the frame members 56 and '51 of the first structural embodiment described In general, the arrangement illustrated in Figs. 9 through 13 differs from that of the first described structure in that all parts of the five control units I I4 are arranged in axial alignment along the high speed shaft I2I. This, of course, necessitates a different structural version of the latching elements I I1 and a correspondingly different arrangement of the operating magnets I I9 individual to the five control units. Specifically, the sleeve I'I5 upon which the low speed camming elements II5 are adjustably supported, together with the driving gear I45 for this sleeve are journalled for free rotation about the high speed shaft I2I, the gear I45 being connected to be driven'from the shaft I2I by means of the gears I 4| I42 and I44. The structural arrangement of the sleeve II5'andthe parts carried thereby for adjustably supporting'the camming elements I I5 is exactly the same as the structure included in the first embodiment of the mechanism to support'the'camming elements I5. Similarly the composite ring and spring washer structure for adiustably supporting the high speed camming elements H6 upon the sleeve I62 is an exact duplicate of the above-described structure for supporting the'camming elements I6 upon the sleeve 62. Further, the camming elements H5 and H6 per se are identical in peripheral pattern with the-camming elements I5 and I6. In the second embodiment of the mechanism, however, a

slightly modified arrangement is provided for releasably locking the camming element I I6 against rotation relative to the shaft I2 I. Specifically, this arrangement comprises a centrally apertured cup-shaped clamping member I92 telescoped over the shaft I2I and having its periphery pressed against the right spacing disc I68 by axial thrust exerted thereon through a sleeve I93. The required thrust is produced by means of an adjustable camming element I94 of U-shaped cross section having legs which straddle the extended end of the shaft and engage flats I2Ia along opposite sides thereof to prevent rotation relative to the shaft. This camming element presses against the right end of the sleeve I93 through the hub Id which supports the driving gear I49. It is provided with camming edges I94a formed along the two legs thereof which are engageable with a pin I95 to produce axial movement of the sleeve I93 in response to lateral movement of the element I94 relative to the shaft. A screw I91 threaded into the base portion of the element I94 and having an end engageable with the side of *the shaft IZI is provided to produce the required lateral movement of the element I94 relative to the shaft. A U-shapedretaining member I96 straddles the camming element I94 and has apertured leg ends cooperating with the shaft I2 I. to retain the camming element I94 on the shaft. With the described arrangement, movement of the pin I95 up the camming edges; I94a of the element I94 is produced when the screw I9! is threaded into the base leg of this element. Thus, the element I94 is moved tojthe left from the position shown in Fig. 10 of the drawings to exert an axial thrust upon the clamping element I92 through the gear hub I-4Ila and the sleeve I93. This thrust serves to clamp the camming elements II6 against the plate I63 and thus prevent rotation of these elements relative to the shaft I 2I. Conversely, as the screw I91 is screwed away from the shaft I2 I, the pin I95 rides down the camming edges I94a to relieve the thrust exerted upon the clamping element I92 through the sleeve I93 and thus release the camming elements I I6 for rotation relative to the shaft l2].

As best shown in Figs. 14 and 15 of the drawings, the latching elements II'I, which are cooperable with the camming elements II 5 and I I6 to arrest operation of the mechanism in the manner explained above, are in the form of internested U-shaped members having their legends pivotally supported upon the stationary shaft I35. The camming and locking noses I 21 and I34 of these elements are formed integral with the 0pposite legs thereof to project downwardly in radial alignment with the respectively associated camming elements H5 and H6. Thus the noses IZ'Ia and I34a of the inner latching element I I'm are illustrated in Figs. 12 and 14 of the drawings as projecting downward from the legs of'this element in radial alignment with the camming elements H511 and II6a. Similarly, the outer latching element II'Ie is provided with camming and locking noses [21c and I 342 projecting downward from the legs thereof to overlie the peripheries of the camming elements II5e and II6e respectively. The latching elements II! are also provided with upwardly extending armature pieces I I8 which are respectively cooperable with the associated magnets 9 to pivot the latching elements on a selective basis to positions wherein the camming and locking noses thereof are engageable with the peripheries of the associated camming elements I I5 and H6. Specifically, these armature parts are structurally so arranged that the armature ends thereof are disposed in alignment. and in spaced apart relationship between the frame members I56 and I51. The associated magnets II9 are similarly arranged in alignment between the two frame members and are mounted upon a cross member I! extending between these frames members. Normally, the latching elements I I1 are restrained in retracted settings, wherein the legs thereof engage the base of an L-shaped stop bracket I9Ia carried by the cross member I9 I by means of coil springs I29 tensioned between the armature parts IIB thereof and a second cross member I90 extending between the two frame members I56 and I51. The rocker bar I50 which carries the movable motor reversing contact I52 extends beneath the nested latching elements H1 and is pivotally supported by the stationary shaft I35, so that when any one of the latching elements is operated, the rocker bar is correspondingly actuated to control the setting of the movable contact I52. This rocker bar is normally held in its retracted position by means of a coil spring II tensioned between the bracket I9Ia and the arm I52a upon which the contact I52 is mounted. As best shown in Fig. 13 of the drawings, the motor reversing relay I46 and the contact spring assembly associated therewith are fixedly mounted upon the frame member I51 to the outside thereof.

As indicated above, the mode of operation of thedescribed second embodiment of the mechanism is exactly the same as explained above with reference to Fig. l of the drawings. Thus, when any one of the magnets I I 9 is energized to select a predetermined setting which is to beimparted to the shaft I2I, the motor I 36 supported between the frame members I55 and I51 is energized to drive the shaft I2! at relatively high speed through the driving connection afforded by the clutch I55 and the meshing gears I38, I39 i i and I40. Such rotation of the shaft I 2| results in low speed rotation of the sleeve I15 through the driving connection afforded by the gears I4I, I42, I44 and I45. Concurrently with energization of the motor I35, the selected magnet II9 operates to rotate the associated latching elements II1 so that the camming and locking noses I21 and I 34 thereof are operatively associated with the peripheries of the associated camming elements H5 and I I6. From this point on, the operation of the mechanism proceeds in the exact manner explained above, it being noted in this regard that the initial direction of rotation of the motor is determined by the setting initially imparted to the movable contact H5, and that reverse rotation of the motor may or may not be required, depending upon the setting" of the shaft I2I at the time operation of the mechanism is initiated. The manner in which the settings of the camming elements II5 and II 6 relative to the sleeves I15 and I62 may be changed to change the tuning shaft settings obtainable under the control of the five control units is exactly the same as explained above with reference to the first embodiment of the mechanism. It will be noted that in the second embodiment of the mechanism no control unit is provided for determining the limits of the rotational ranges of the two shafts H5 and I2I. Such a unit may be provided if required, however, in a manner entirely evident from the preceding explanation.

While there have been described what are at present considered to be the preferred embodiments of" the invention, it will be understood that various modifications may be made therein which 14 are within the true spirit and scope of the invention as defined in. the appended claims.

I claim:

1. In a mechanism for moving the tuning shaft of tunable wave signaling apparatus to a predetermined setting within a predetermined rotational range, a control unit for stopping said shaft when rotated to said predetermined setting comprising a rotatable camming element having a rotational range corresponding to said predetermined rotational range and operative to determine said predetermined setting of said shaft with approximate accuracy, a latching element having a portion engaging said camming element, driving means for rotating said camming element in either direction, switch means coupled to said latching element for controlling said driving means, said camming element having a portion engaging said portion of said latching element when said camming element is rotated in one direction to a predetermined position corresponding to said predetermined shaft setting, with said portion of said latching element sliding over said portion of said camming element when said camming element is rotated in the other direction past said predetermined position, said camming element operating through said latching element and said switch means to control the direction of rotation of said driving means in accordance with the position of said camming element and being operative to reverse the direction of said driving means when said camming element is rotated past said predetermined position in said other direction, to rotate said camming element in said one direction back to said predetermined position, and rotatable means having a rotational range several times greater than the rotational range of said camming element and cooperable with said latching element when said latching element is operated in, said predetermined manner to stop rotation of said camming element when rotated precisely to said predetermined position.

2. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to any one of a number of different predetermined settings within a predetermined rotational range, comprising a pair of rotatable members having rotational ranges respectively corresponding to said predetermined rotational range, the rotational range of one of said members being several times greater than the rotational range of the other of said members, control units respectively corresponding to said predetermined shaft settings and individually including rotatable elements respectively carried by said members, the rotatable elements carried by said other member being respectively operative to determine said predetermined shaft settings with approximate accuracy and the rotatable elements carried by said one member being respectively operative to determine said predetermined shaft settings with precision accuracy, means for driving said members at different speeds respectively commensurate with their respective rotational ranges, control means for said driving means for controlling the direction. of rotation thereof, selectively operable latching elements individual to said control units and respectively engageable with the rotatable elements thereof to lock said members against relative rotation in predetermined positions respectively corresponding to said predetermined shaft settings in response to rotation of said members to said predetermined positionsv in one direction only, said control means being coupled to said latching elements and operated thereby to control the direction of rotation of said driving means in accordance with the positions of said rotatable elements with respect to said pre-- determined positions, said control means operating to reverse said driving means to thereby reverse the direction of rotation of said members in response to rotation of said members in the other irection through positions corresponding to any operated one of said latching elements.

3. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to any one of a number of different predetermined settings within a predetermined rotational range, comprising a pair of radially spaced rotatable mem bers having rotational ranges respectively corresponding to said predetermined rotational range, the rotational range of one of said members being several times greater than the rotational range of the other of said members, control units respectively corresponding to said pre determined shaft settings and individually in cluding rotatable elements respectively carried by said members, the rotatable elements carried by said other member being respectively operative to determine said predetermined shaft settings with approximate accuracy and the rotatable elements carried by said one member being, respectively operative to determine said predetermined shaft settings with precision accuracy, means for driving said members at different speeds respectively commensurate with their respective rotational ranges, control means for said driving means for controlling the direction of rotation thereof, latching elements individual to said control units and bridging the rotatable elements thereof, said latching elementsbeing selectively operable to lock said members against relative rotation in different predetermined positions respectively corresponding to said predetermined shaft settings in response to rotation of said members to said predetermined positions in one direction only, said control means being coupled to said latching elements and operated thereby to control the direction of rotation of said driving means in accordance with the positions of said rotatable elements associated with an operated latching element, said control means operating to reverse the direction of said motor and thereby reverse the direction of rotation of said members in response to rotation of said members in the other direction through said predetermined positions corresponding to the operated one of said latching elements. I

4. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to any one of a number of different predetermined settings within a predetermined rotational range, comprising a pair of coaxial and rotatable members having rotational ranges respectively corresponding to said predeterined rotational range, the rotational range'of one of said members being several times greater than the rotational range of the other of said members, control units respectively corresponding to said predetermined shaft settings and individually including rota table elements respectively carried by said members, the rotatable elements carried by said other member being respectively operative to determine said predetermined shaft settings with approximate accuracy and the rotatable elements carried by said one member being respectively operative to determine said predetermined shaft settings with precision accuracy, means for driving said members at different speeds respectively commensurate with their respective rotational ranges, and internested U-shaped latching elements individual to said control units, said latching elements being selectively operable to engage the rotatable elements of their associated control units and thus arrest rotation of said members in different positions respectively corresponding to said predetermined shaft settings.

5. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to any one of a number of different predetermined settings 7 within a predetermined rotational range, comprising a pair of coaxial and rotatable members having rotational ranges respectively corresponding to said predetermined rotational range, the rotational range of one of said members being several times greater than the rotational range of the other of said members, control units respectively corresponding to said predetermined shaft settings and individually including rotatable elements respectively carried by said members, the rotatable elements carried by said other member being respectively operative to determine said predetermined shaft settings with approximate accuracy and the rotatable elements carried by said one member being respectively operative to determine said predetermined shaft settings with precision accuracy, means for driving said members at different speeds respectively commensurate with their respectively rotational ranges, internested U-shaped latching elements individual to said control units and bridging the rotatable elements thereof, said latching elements being selectively operable to lock said members against relative rotation in different predetermined positions respectively corresponding to said predetermined shaft settings in response to rotation of said members to said predetermined positions in one direction only, said members being rotatable in either direction toward any one of said predetermined positions, and means controlled by any operated one of said latching elements for reversing the-direction of rotation of said members in response to rotation of said members in the other direction through positions corresponding to the operated one of said latching elements. I

6. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to a predetermined setting within a predetermined rotational range, including in combination, a pair of elements rotatable at different speeds to predetermined relative positions corresponding to said predetermined shaft setting and respectively operative to determine said predetermined setting of said-shaft with approximate and pro-- cision accuracy, driving means for rotating said shaft and said elements in either direction, latching means having portions for engaging said rotatable elements, and control means for said driving means operated by said latching means for causing said driving means to rotate said elements from any position toward said predetervmined positions in the direction to reach said predetermined positions with the least movement,

ments are rotated in the direction opposite to said one direction, one of said rotatable elements operating said control means through said latching means for causing said driving means to reverse direction when said one rotatable element rotates through said predetermined position in said opposite direction so that said rotatable elements reverse and rotate in said one direction to said predetermined positions.

7. A mechanism for moving the tuning shaft of tunable wave signaling apparatus to a predetermined setting within a predetermined rotational range, including in combination, a pair of elements rotatable at different speeds to predetermined relative positions corresponding to said predetermined shaft setting and respectively operative to determine said predetermined setting of said shaft with approximate and precision accuracy, driving means for rotating said shaft and said elements in either direction, and control means for said driving means operatively connected to said rotatable element which determines the approximate setting of said shaft for causing said driving means to rotate said elements from any position toward said predetermined positions in the direction to reach said predetermined positions with the least movement, said control means having portions interlocking with said portions of said rotatable elements for preventing further rotation thereof when said rotatable elements are rotated in one direction to said predetermined positions, said portions of said control means being shaped to slide over said rotatable elements so that said rotatable elements continue through said predetermined positions when said rotatable elements are rotated in the direction opposite to said one direction, said rotatable element which determines the approximate setting of said shaft operating through said control means to cause said driving means to reverse direction when said rotatable elements rotate through said predetermined positions in said opposite direction so that said rotatable elements reverse and rotate in said one direction to said predetermined positions.

LEO D. SACRE'.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

